An Australian air force base was put on alert while Russian strategic bombers conducted exercises in neutral waters off Indonesia, a move experts said showed Moscow was looking to extend its influence in the Pacific.

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The base in Darwin was briefly put on a state of “increased readiness” in early December during the Russian exercises, which, according to the Russian Ministry of Defence, involved two nuclear-capable Tu-95MS bombers and more than 100 personnel.

One of Australia’s foremost national security experts, Peter Jennings of the Australian Strategic Policy Institute, said the exercises showed Russia was again extending its influence to the peripheries of the world. “It is a reminder Russia is here and wants to be a player in Pacific security and will use military force to demonstrate that,” he told the ABC, which first reported the story.

The aircraft took off from Indonesia’s Biak airfield, on an island north of Papua, and stayed in the air for more than eight hours. The aircraft flew only above neutral waters, according to the Russian military.

“Flights over neutral waters in Arctic, northern Arctic, Black and Caspian seas, and Pacific Fleet are conducted regularly by long-range aircraft,” its defence ministry said in a statement. “All the missions of the Russian Aerospace Forces are carried out in strict accordance with the international air law.”

The Australian Department of Defence confirmed to Guardian Australia “there was a brief period of increased readiness” in early December but said the base was not in lockdown.

“The [Australian Defence Force] maintains appropriate levels of readiness and posture to respond to evolving circumstances,” the spokesman said. “In early December there was a brief period of increased readiness. There were no instances of unalerted or unscheduled foreign aircraft operating in Australian airspace during this period.”

It’s not the first time Russia has sought to demonstrate influence in the Pacific. Last year, it was revealed Russia had sent a secret shipment of 20 containers of weapons and military hardware to its newfound regional partner, Fiji. The shipment was followed by Russian military personnel, who were to train the Fijians in the use of the weapons.

In 2014, Russian naval vessels moved to the north of Australia, days before the G20 summit in Brisbane and at a time of heightened tensions between Moscow and Canberra.

In a 2015 paper, Alexey Muraviev, a strategic analyst and Russian military expert at Perth’s Curtin University, said Russia had tangibly intensified its engagement in the Asia-Pacific since about 2000.

Muraviev argued the 2014 Ukraine tensions and a need to diversify trade had “deepened Moscow’s long-standing impulse to re-engage with both Asia and the Pacific”.

“Economically, Moscow is responding to the rise of the Asia-Pacific as an engine of the global economy,” he wrote. “Politically, Moscow sees in the region a number of potential partners also striving to establish a multipolar world, notably China. In the military-strategic sphere, Russia is sensitive to the risk of armed conflict on its eastern flank.”

Australia’s acting opposition leader, Tanya Plibersek, said it appeared Russia had abided by international laws and norms during the exercises. She made no other comment on the response of the Australian defence force.

“I think it is very important that any country doing military exercises abides by laws and norms, international laws and norms, and the reporting suggests that this has been the case in this instance,” Plibersek said on Saturday.

Jennings said defence forces might have feared the bombers were being used to gather intelligence.

“There would be concerns about Russian intelligence gathering because they wouldn’t come this far south without wanting to look at the one significant Allied presence in this part of the world, which is what operates out of Darwin and RAAF base Tindal further south,” he told the ABC. “So there would be have been intelligence gathering we would have been geared to resist.”